Small interfering RNA (siRNA) has been shown to bind to target mRNA and suppress of protein expression from the target mRNA. Due to their effective and sequence-specific gene silencing, siRNA molecules have been highlighted for application as new potential therapeutics. In particular, siRNA-based therapeutics, compared to conventional antisense oligonucleotide-based therapeutics, may exert excellent gene-silencing activity even at low doses and have low cytotoxicity, thus being relatively safe. In order to realize these advantageous effects of siRNA, it is essential that the siRNA is effectively delivered into target cells that express RNA of interest. The siRNA can be delivered, for example, by an organic carrier (polymer) as disclosed in Korean Pat. Publication No. 10-2007-0061770 (published in Jun. 14, 2007) entitled “siRNA-hydrophilic polymer conjugates for intracellular delivery of siRNA and preparation method thereof”.
However, conventional carrier systems of siRNA, including the above-mentioned patent publication, still face multiple barriers in delivering siRNA to their target cells, including uptake into cells across the plasma membrane and escape from the endosome into the cytoplasm. Also, the conventional carrier systems have low delivery efficiency since siRNA may be susceptible to nuclease digestion in vivo, and do not ensure safety upon application to humans since organic or inorganic materials are employed as carriers.